Low temperature sintering ceramic composition for use in high frequency, method of fabricating the same and electronic component

ABSTRACT

A low temperature sintering ceramic composition that can be sintered at a temperature equal to or less than 1000° C. and has low dielectric constant and dielectric loss in a high frequency region of 17 Ghz or more, an electronic component using the same and a method of fabricating the low temperature sintering ceramic are provided. The composition comprises MgO and SiO 2  in sum total in the range of from 64.0 to 99.2% by mass; Bi 2 O 3  in the range of from 0.4 to 33.0% by mass; Li 2 O in the range of from 0.4 to 3.0% by mass; and MgO and SiO 2  are contained in the molar ratio of from 2:1 to 2:3.5, at least part thereof being contained as a complex oxide of Mg and Si.

TECHNICAL FIELD

The present invention relates to a low temperature sintering ceramic(porcelain) composition that is low in the dielectric constant and thedielectric loss and an electronic component using the same and a methodof fabricating the low temperature sintering ceramic.

BACKGROUND ART

In recent years, in facing with an advanced information age, higherspeed, higher integration and higher density packaging are demanded forsemiconductor devices. In order to attain a higher speed in thesemiconductor devices, in addition to shortening a wiring length and soon, it is indispensable to increase the signal propagation velocity on acircuit; in this connection, the signal propagation velocity is ininverse proportion to a square root of the dielectric constant of asubstrate material; accordingly, a substrate material lower in thedielectric constant is necessary. Furthermore, in order to attain thehigher integration and the higher density packaging, wiring materialslow in the specific resistance (Ag, Au, Cu and so on) are demanded touse; however, since these metals are low in the melting point, in amulti-layered printed wiring board or the like in which after a wiringpattern is printed a substrate is sintered, it is necessary to use asubstrate material capable of sintering at low temperatures.Accordingly, since alumina substrates (dielectric constant: from 9 to9.5, sintering temperature: substantially 1500° C.) that have been sofar widely used as a substrate material for use in electronic componentsare not suitable for high frequency printed circuit boards, in place ofthis, a material that is lower in the dielectric constant and capable ofsintering at low temperatures is in demand. In addition, lower loss inmicrowave and millimeter wave regions is also in demand.

In this connection, recently, as a low dielectric constant substratematerial capable of coping with higher speeds, a glass ceramic materialmade of glass and inorganic filler is under study. This kind of glassceramic material, being such low in the dielectric constant assubstantially from 3 to 7, is suitable for insulating substrates for usein high frequency, and in addition to the above, being capable ofsintering at temperatures from 800 to 1000° C., is advantageouslycapable of sintering simultaneously with Ag, Au, Cu and so on low in theconductor resistance.

For instance, in JP-A-2000-188017 (U.S. Pat. No. 6,232,251), a ceramiccomposition for use in high frequency that includes a glass phasecapable of precipitating a diopside (CaMgSi₂O₆) type crystal phase andan oxide containing Mg and/or Zn and Ti as the filler and is capable ofsintering at a temperature equal to or less than 1000° C. is disclosed.Furthermore, in JP-A-2001-240470, a printed wiring board for use in highfrequency that is made of a crystallized glass component containingSiO₂, Al₂O₃, MO (M denotes an alkaline earth metal element) and Pb and akind of filler selected from a group of Al₂O₃, SiO₂, MgTiO₃, (Mg,Zn)TiO₃, TiO₂, SrTiO₃, MgAl₂O₄, ZnAl₂O₄, cordierite, mullite, enstatite,willemite, CaAl₂Si₂O₃, SrAl₂Si₂O₈, (Sr, Ca)Al₂Si₂O₈ and forsterite isdisclosed.

In addition, low temperature sintering ceramic compositions in whichboron (B) is used as a sintering aide has been proposed (SeeJP-A-2000-037661, JP-A-2002-173367, etc.).

However, the conventional glass ceramic material, though low in thedielectric constant, is such high as 20×10⁻⁴ or more in the dielectricloss (tan δ) in a high frequency region of a signal frequency of 10 GHzor more, that is, substantially in the range of from 5×10³ to 8×10³ interms of the Qf value; accordingly, it does not have the characteristicsenough to put into practical use as the substrate material for highfrequency. For example, the ceramic composition of JP-A-2000-037661 hasa Qf value of at most 0.5×10³ and the composition of JP-A-2002-173367has a Qf value on the order of 5×10³. The Qf value here denotes aproduct of a measurement frequency (f/GHz) and Q (≅1/tan δ).

Accordingly, the present invention intends to provide a low temperaturesintering ceramic composition that can be sintered simultaneously with alow resistance metal such as Ag, Au, Cu or the like and realize lowdielectric constant and the low dielectric loss in a high frequencyregion, and a fabricating method of the low temperature sinteringceramic.

DISCLOSURE OF THE INVENTION

The present inventors, after studying hard to overcome the problems,found that a composition in which Bi₂O₃ and Li₂O are added at particularratios to a complex oxide containing Mg and Si can be sintered at atemperature in the range of substantially from 850 to 1000° C., and alow temperature sintering ceramic obtained by sintering such acomposition has low dielectric constant and low dielectric loss, andthereby the present invention is accomplished.

That is, the present invention provides the following low temperaturesintering ceramic composition, electronic components using the same andmethod of fabricating low temperature sintering ceramics.

(1) A low temperature sintering ceramic composition containing Mg, Si,Bi and Li as constituent elements, wherein the composition comprises

MgO and SiO₂ in sum total in the range of from 64.0 to 99.2% by mass;

Bi₂O₃ in the range of from 0.4 to 33.0% by mass;

Li₂O in the range of from 0.4 to 3.0% by mass; and

MgO and SiO₂ are contained in the molar ratio of from 2:1 to 2:3.5, atleast part thereof being contained as a complex oxide of Mg and Si.

(2) The low temperature sintering ceramic composition according to above1, wherein the composition comprises

MgO and SiO₂ in sum total in the range of from 75.0 to 98.0% by mass;

Bi₂O₃ in the range of from 1.5 to 24.5% by mass;

Li₂O in the range of from 0.5 to 3.0% by mass.

(3) The low temperature sintering ceramic composition according to above1 or 2, wherein the complex oxide is a forsterite system crystal phaseand/or enstatite system crystal phase; and

at least part of Bi₂O₃ and Li₂O is contained as a Bi₂O₃—SiO₂ systemcrystal phase and a Li₂O—SiO₂ system crystal phase.

(4) The low temperature sintering ceramic composition according above 3,wherein the forsterite system crystal phase and/or enststite systemcrystal phase are contained by 60% or more of a total volume of theceramic.

(5) The low temperature sintering ceramic composition according to anyone of above 1 to 4, wherein a Qf value is 10, 000 or more.

(6) An electronic component comprising a wiring pattern on the lowtemperature sintering ceramic composition according to any one of above1 to 5.

(7) The electronic component according to above 6, wherein the wiring isformed by sintering a conductive paste containing at lease one metalselected from Ag, Au and Cu.

(8) A method of fabricating a low temperature sintering ceramiccomposition comprising:

molding a raw material powder containing one or both of a mixture of MgOand SiO₂ that contains MgO and SiO₂ at a molar ratio in the range offrom 2:1 to 2:3.5 and a complex oxide thereof in the range of from 64.0to 99.2% by mass, Bi₂O₃ in the range of from 0.4 to 33.0% by mass andLi₂O in the range of from 0.4 to 3.0% by mass into a predetermined shapefollowed by sintering at a temperature in the range of from 850 to 1000°C.

(9) The method according to above 8, wherein the raw material powdersare fine powders having a particle size of 2.0 μm or less.

DETAILED DESCRIPTION OF THE INVENTION

(A) Porcelain Composition

A low temperature sintering ceramic composition according to theinvention is a low temperature sintering ceramic composition in whichMgO and SiO₂ are contained in sum total in the range of from 64.0 to99.2% by mass, Bi₂O₃ is contained in the range of from 0.4 to 33.0% bymass and Li₂O is contained in the range of from 0.4 to 3.0% by mass;wherein MgO and SiO₂ are contained at a molar ratio of MgO to SiO₂ inthe range of from 2:1 to 2:3.5 and at least part thereof is contained asa complex oxide of Mg and Si.

When Bi₂O₃ and Li₂O are contained in the complex oxide that contains Mgand Si, during heating, a Bi₂O₃—SiO₂ system liquid phase and Li₂O—SiO₂system liquid phase are formed, and through a liquid phase reactionthereof, the sintering can be performed at a temperature in the range ofsubstantially from 850 to 1000° C.

The low temperature sintering ceramic composition according to theinvention contains MgO and SiO₂ in sum total in the range of from 64.0to 99.2% by mass and preferably in the range of from 75 to 98% by mass;Bi₂O₃ in the range of from 0.4 to 33.0% by mass and preferably in therange of from 1.5 to 24.5% by mass; and Li₂O in the range of from 0.4 to3.0% by mass and preferably in the range of from 0.5 to 3.0% by mass(100% by mass in sum total).

When MgO and SiO₂ are contained less than necessary, the high Qfcharacteristics due to these primary phases thereof are damaged. On theother hand, when these are contained more than necessary, the lowtemperature sintering properties are lost. When Bi₂O₃ is contained lessthan necessary, the low temperature sintering properties cannot berealized. Furthermore, when it is contained more than necessary, inaddition to the bulk density becoming 4 g/cm³ or more, since2Bi₂O₃.3SiO₂ becomes a primary phase, the dielectric constant becomesunfavorably high. When Li₂O is contained less than necessary, the lowtemperature sintering properties cannot be realized. Still furthermore,when it is contained more than necessary, the dielectric loss in a highfrequency region of 17 GHz becomes such high as 10×10⁻⁴ or more;accordingly, a high Qf value cannot be realized.

MgO and SiO₂ are contained at a molar ratio of MgO to SiO₂ in the rangeof from 2:1 to 2:3.5. When the molar ratio of MgO/SiO₂ is either lessthan 2/3.5 or more than 2/1, the sintering properties deteriorate; thatis, the ceramic cannot be densified. A preferable range is from 2:1.5 to2:3.0.

A complex oxide of Mg and Si may be any one as far as the molar ratio ofMgO to SiO₂ satisfies the above range; however, a complex oxide thatsatisfies 1≦n≦2 when expressed by n MgO SiO₂ is made a primarycomponent. A complex oxide crystal at n=2 (2MgO.SiO₂)is known asforsterite and one at n=1 is known as enstatite.

Accordingly, the low temperature sintering ceramic according to theinvention, while primarily containing a forsterite system crystal phaseand/or an enstatite system crystal phase, is further constituted mainlyof a Bi₂O₃.SiO₂ system crystal phase and a Li₂O—SiO₂ system crystalphase. Here, the “forsterite system crystal phase” denotes forsteriteand crystal phases similar to this and may contain the same type ofcrystal phases constituted of the components of the ceramic composition(for instance, Li₂MgSiO₄) . The situations are similar also to anenstatite system crystal phase, a Bi₂O₃—SiO₂ system crystal phase and aLi₂O—SiO₂ system crystal phase.

The specific molar ratios of the respective phases, as far as targetvalues of the physical properties can be realized, are not restricted;however, ordinarily, the forsterite system crystal phase and/orenststite system crystal phase are contained by 60% or more of a totalvolume of the ceramic, preferably by 80% or more, more preferably by 90%or more and still more preferably by 95% or more.

Furthermore, as far as the effect of the invention is not damaged, aSiO₂ system crystal phase and so on and an amorphous phase and so on maybe contained.

The low temperature sintering ceramic according to the invention has theQf value of 10,000 or more and can be densified to the bulk densityratio (relative value obtained by dividing the observed density with thetheoretical density calculated for a completely dense material) of 95%or more by sintering in the temperature range of from 850 to 1000° C.

(B) Method of Fabricating Low Temperature Sintering Ceramic

The low temperature sintering ceramic according to the invention can befabricated by molding a raw material powder in which a mixture of MgOand SiO₂ in which MgO and SiO₂ are contained at a molar ratio of from2:1 to 2:3.5 and/or a complex oxide thereof is contained in the range offrom 64.0 to 99.2% by mass, Bi₂O₃ is contained in the range of from 0.4to 33.0% by mass and Li₂O is contained in the range of from 0.4 to 3.0%by mass into a predetermined shape followed by sintering at atemperature in the range of from 850 to 1000° C.

Mg and SiO₂ that are primary raw materials may be a mixture of therespective metal oxides or a mixture obtained by adding a necessaryamount of SiO₂ and MgO to a complex oxide such as forsterite (2MgSiO₂).MgO and SiO₂ that can be used as starting raw materials can be added,other than in the form of oxide powder of the respective metals, also inthe form of carbonates, acetates, nitrates and so on that can form oxidein the course of the sintering.

To the above raw material of primary components, Bi₂O₃ powder and Li₂Opowder as the sintering aide are added by the above ratio, preferably,so that the primary components raw material may be contained in therange of from 75 to 98% by mass; Bi₂O₃ in the range of from 1.5 to 24.5%by mass; and Li₂O in the range of from 0.5 to 3.0% by mass, followed bymixing. Bi₂O₃ and Li₂O also can be added, other than in the form ofoxide powder of the respective metals, in the form of carbonates,acetates, nitrates and so on that can form an oxide in the course of thesintering.

Raw material powders of Mg₂SiO₄, SiO₂, MgO, Bi₂O₃, Li₂O and so on, inorder to heighten the dispersibility thereof and to obtain desirabledielectric constant and low dielectric loss, are preferably renderedfine powders of 2.0 μm or less, particularly 1.0 μm or less.

The powder mixture obtained by adding at the above ratio followed bymixing, after a binder is appropriately added, is molded into anarbitrary shape by means of such as a metal mold pressing, extrusionmolding, doctor blade method, rolling and so on, sintered in an oxygenatmosphere or a no-oxidizing atmosphere of such as N₂, Ar and so on at atemperature in the range of from 850 to 1000° C., particularly from 850to 950° C. for from 1 to 3 hr, and thereby high bulk density ratio of95% or more can be obtained. When the sintering temperature at this timeis lower than 850° C., the ceramic cannot be sufficiently densified; onthe other hand, when it exceeds 1000° C., though the densification canbe attained, low melting point conductors such as Ag, Au, Cu and so onbecome difficult to use as the wiring material.

According to the method according to the invention, a more activereaction is generated between a solid phase that is a complex oxide ofMg and Si and a liquid phase of Bi₂O₃—SiO₂ and Li₂O—SiO₂ systems; as aresult, the ceramic can be densified with a slight amount of sinteringaide. Accordingly, an amount of an amorphous phase in grain boundarythat causes an increase in the dielectric loss can be suppressed to theminimum amount. As mentioned above, according to the fabricating methodaccording to the invention, in the ceramic, at least the forsteritesystem crystal phase and/or enstatite system crystal phase that containsMg and Si, the Bi₂O₃—SiO₂ system crystal phase and the Li₂O—SiO₂ systemcrystal phase can be precipitated, and thereby, the dielectric constantcan be controlled to 9 or less even at substantially 17 GHz and aceramic for use in high frequency that is low in the dielectric loss,accordingly, high in the Qf value can be obtained.

(C) Applications of Ceramic Composition

The ceramic composition according to the invention can be sintered at atemperature in the range of from 850 to 1000° C.; accordingly, it can beused as an insulating substrate of a printed wiring board whereparticularly Ag, Au, Cu and so on are wired. In the case of a printedwiring board being fabricated by use of such ceramic composition, forinstance, a powder mixture compounded as mentioned above is formed intoa green sheet for use in the formation of insulating layer by means of aknown tape formation method such as a doctor blade method, extrusionmolding method and so on. Thereafter, on a surface of the green sheet,as a wiring circuit layer, by use of a conductive paste containing atleast one kind of metal of Ag, Au and Cu, in particular, Ag powder, awiring pattern is printed circuit pattern-like according to a screenprinting method and so on. Optionally, through holes and via-holes maybe formed in the sheet followed by filling them with the aboveconductive paste. Thereafter, a plurality of green sheets is laminatedunder pressure followed by sintering under the above conditions, andthereby the wiring layer and the insulating layer can be simultaneouslysintered.

Accordingly, the present invention also encompasses electroniccomponents containing these circuits. The wiring pattern may alsoinclude a pattern comprising a material other than the materialsmentioned above as long as it can be used under the sintering condition.Typical but not limiting examples thereof include a resistor formed of amaterial having a high-melting point. The electronic component may becomposed of these wiring patterns or contain discrete devices mountedthereon.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, the present invention will be specifically describedwith Examples and comparative Examples; however, the present inventionis not restricted thereto.

EXAMPLES 1 TO 34

Mg₂SiO₄, MgO, SiO₂, Bi₂O₃ and Li₂CO₃ each having an average particlediameter of 1 μm or less were blended so that content ratios in terms ofoxide might be ratios shown in Table 1 (Mg₂SiO₄, MgO, SiO₂ are shown inthe third and fourth columns in terms of MgO and SiO₂ a while Bi₂O₃ andLi₂CO₃ are shown in the fifth column as “liquid phase” in terms of Bi₂O₃and Li₂O. The same as in the following tables.). To each of thesemixtures, an organic binder (Denka Butyral #3000-K, product manufacturedby DENKI KAGAKU KOGYO KABUSHIKI KAISHA), a plasticizer(butylphthalylbutyl glycolate, manufactured by Wako Pure ChemicalIndustries Co., Ltd.), and toluene were added followed by preparing agreen sheet having a thickness of 150 μm by means of the doctor blademethod. Then, five of the green sheets were stacked and subjected to thethermocompression bonding under a pressure of 150 kg/cm² at 70° C. Theobtained laminate body, after degreasing by heating the sheets in air at500° C. so that the organic components may be decomposed and/or andevaporated, was sintered in air under the conditions shown in Table 1,and thereby ceramic for use in a multi-layered substrate was obtained.In Table 1, total contents of Mg and Si in raw material mixtures (interms of oxide) and MgO/SiO₂ ratios are shown together.

The dielectric constant and the dielectric loss were measured of each ofthe obtained sintered bodies according to the following methods. Themeasurements were performed according to JIS R1627 “Testing method fordielectric properties of fine ceramics at microwave frequency”. That is,the ceramic for use in multi-layered substrate was cut into a disc-likesample a having diameter of from 1 to 5 mm and a thickness of from 2 to3 mm, both end faces of the disc-like sample were short circuited by useof two parallel conductive plates to form a dielectric resonator. Theresonance characteristics and the no-load Q at TE011 mode of thedielectric resonator were measured in the range of from 17 to 20 GHz byuse of a network analyzer (Model 8722C manufactured by Hewlett-PackardCorp.) followed by calculating the dielectric constant and thedielectric loss (tan δ) further followed by calculating the Qf valuefrom a measurement frequency and Q (=1/tan δ). Results are shown inTable 2.

Furthermore, by performing X-ray diffractometry of the respectivesamples and comparing with X-ray diffraction peaks of standard samplesto identify constituent phases of the ceramics, the forsterite crystalphase (2MgSiO₄) and/or enstatite crystal phase (MgSiO₄), the Bi₂O₃—SiO₂system crystal phase (typical in eulytite 2Bi₂O₃.3SiO₄) and a Li₂O—SiO₂system crystal phase each were confirmed to be present.

As obvious from the above results, all of the ceramics according to theinvention that include MgO, SiO₂, Bi₂O₃ and Li₂O in the range of theinvention and in which, as crystal phases, the forsterite system crystalphase and/or the enstatite system crystal phase, the Bi₂O₃—SiO₂ systemcrystal phase, and the Li₂O—SiO₂ system crystal phase are mainlyprecipitated exhibit excellent values of the dielectric constant of 9 orless and the Qf value of 10,000 or more. However, when the content of Biis increased, the bulk density tends to increase and reaches 4.0 at theupper limit of Bi that is 33.0% by mass in the invention (Example 33).

COMPARATIVE EXAMPLES 1 TO 10

Mg₂SiO₄, MgO, SiO₂, Bi₂O₃ and Li₂CO₃ each having an average particlediameter of 1 μm or less were blended so that compositions in terms ofoxide may be ratios shown in Table 1. These compositions were sinteredsimilarly to Examples 1 through 34 under the conditions shown in Table1, and thereby ceramics for use in multi-layered substrate wereobtained. Results are collectively shown in Table 2.

A sample where Bi₂O₃ and Li₂O were not added could not be sintered atlow temperatures (Comparative Example 1), and a sample where Bi₂O₃ wasadded by less than 0.4% by mass (Comparative Example 10) and sampleswhere Li₂O was added by less than 0.4% by mass (Comparative Examples 3through 7) were not sintered at a sintering temperature in range of thepresent invention. When the amount of Li₂O exceeds 3.0% by mass, thedielectric loss becomes large and the Qf value becomes less than 10,000.Samples where the MgO/SiO₂ ratio exceeds 2/1 (Comparative Examples 8 and9) could not be sintered at a sintering temperature in range or thepresent invention. TABLE 1 Composition Composition Liquid phaseSintering Holding Composition (molar ratio) (% by mass) (% by mass)temperature time No. ratio MgO SiO₂ MgO SiO₂ Bi₂O₃ Li₂O (° C.) (hr)Example 1 93 2 1 53.3 39.7 5.00 2.00 883 1 2 93 2 1.5 43.9 49.1 5.002.00 883 1 3 95 2 1.5 44.8 50.2 3.57 1.43 883 1 4 91 2 1.5 43.0 48.06.43 2.57 883 1 5 93 2 2 37.3 55.7 5.00 2.00 883 1 6 95 2 2 38.1 56.94.50 0.50 904 1 7 95 2 2 38.1 56.9 4.00 1.00 904 1 8 94 2 2 37.7 56.34.50 1.50 910 1 9 93.5 2 2 37.5 56.0 4.50 2.00 910 1 10 94.5 2 2 37.956.6 5.00 0.50 950 1 11 93.5 2 2 37.5 56.0 6.00 0.50 950 1 12 92.5 2 237.1 55.4 7.00 0.50 950 1 13 93 2 2.5 32.5 60.5 5.00 2.00 883 1 14 95 22.5 33.2 61.8 4.00 1.00 885 1 15 95 2 2.5 33.2 61.8 3.00 2.00 885 1 1693 2 2.5 32.5 60.5 6.50 0.50 954 1 17 91 2 2.5 31.8 59.2 8.50 0.50 954 118 93 2 3 28.7 64.3 5.00 2.00 883 1 19 95 2 1.5 44.8 50.2 4.50 0.50 9611 20 95 2 1.5 44.8 50.2 4.00 1.00 961 1 21 95 2 1.3 48.2 46.8 4.00 1.00885 1 22 85 2 2 34.1 50.9 14.50 0.50 950 1 23 90 2 2 36.1 53.9 9.50 0.50950 1 24 98 2 2 39.3 58.7 1.50 0.50 950 1 25 97.5 2 2 39.1 58.4 1.501.00 893 1 26 97 2 2 38.9 58.1 2.50 0.50 955 1 27 96.5 2 2 38.7 57.82.50 1.00 893 1 28 80 2 2 32.1 47.9 19.50 0.50 893 1 29 75 2 2 30.1 44.924.50 0.50 893 1 30 95 2 3 29.3 65.7 4.00 1.00 890 1 31 95 2 3.5 26.368.7 4.00 1.00 890 1 32 69.5 2 2 27.9 41.6 30.00 0.50 908 1 33 66.5 2 226.7 39.8 33.00 0.50 908 1 34 98.5 2 2 39.5 59.0 0.50 1.00 959 1Comparative 1 100 2 1 57.3 42.7 0.00 0.00 1402 3 Example 2 89 2 1.5 42.047.0 7.86 3.14 883 1 3 95 2 2 38.1 56.9 5.00 0.00 910 1 4 95 2 2.5 33.261.8 4.75 0.25 954 1 5 94 2 2.5 32.8 61.2 5.75 0.25 954 1 6 95 2 2 38.156.9 4.70 0.30 950 1 7 95 2 2 38.1 56.9 4.90 0.10 950 1 8 95 2 0.8 59.535.5 4.00 1.00 943 1 9 94 2 0.8 58.9 35.1 4.00 2.00 943 1 10 98.7 2 239.6 59.1 0.30 1.00 959 1

TABLE 2 Bulk density Frequency Dielectric No. (g/cm³) (GHz) constant Q Qf Example 1 3.18 18.2 6.98 707 12862 2 3.25 17.9 7.17 789 14125 3 3.2317.9 7.15 794 14218 4 3.24 17.9 7.20 575 10284 5 3.24 17.9 7.20 95217048 6 3.15 18.3 6.84 3374 61748 7 3.24 18.4 7.15 1115 20516 8 3.2418.5 7.12 604 11174 9 3.24 18.8 7.17 539 10124 10 3.24 19.5 6.98 272553128 11 3.24 20.0 6.98 2332 46644 12 3.22 20.1 6.96 1101 22120 13 3.1718.2 6.80 921 16759 14 3.15 18.3 6.72 1220 22326 15 3.07 18.3 6.67 94717330 16 3.11 19.9 6.62 1007 20031 17 3.14 19.8 6.76 973 19257 18 3.1318.5 6.50 861 15934 19 3.17 18.8 6.87 3559 66902 20 3.16 19.1 6.91 101219322 21 3.21 18.5 6.92 1230 22748 22 3.49 18.9 7.51 2287 43227 23 3.3718.8 7.28 2551 47950 24 3.07 19.6 6.68 1902 37284 25 3.13 18.5 6.87 134324789 26 3.16 18.4 6.96 1729 31792 27 3.17 18.8 6.88 586 11043 28 3.6417.8 7.79 2176 38659 29 3.77 17.5 8.07 2117 36944 30 3.10 18.4 6.42 110520368 31 3.04 18.6 6.21 973 18099 32 3.88 16.9 8.43 2401 40549 33 4.0016.8 8.59 2304 38707 34 3.12 18.9 6.95 814 15428 Comparative 1 2.99 20.76.41 8091 167484 Example 2 3.26 17.9 7.26 462 8275 3 Un-sintered — — — —4 Un-sintered — — — — 5 Un-sintered — — — — 6 Un-sintered — — — — 7Un-sintered — — — — 8 Un-sintered — — — — 9 Un-sintered — — — — 10Un-sintered — — — —

COMPARATIVE EXAMPLES 11 TO 12

A composition prepared similarly to Example 6 except for the use of Binstead of Bi was sintered at 953° C. and found it could not be sinteredat 1 hr sintering. Furthermore, when a composition prepared similarly toExample 8 except for the use of B instead of Bi was sintered at 953° C.for 1 hr, the obtained ceramic composition exhibited enough lowdielectric constant such as 6.86; however, the Q value at 18.8 GHz was410 and the Qf value (7716.3) was less than 10,000. Specificcompositions and results are shown in Tables 3 and 4. TABLE 3Composition Composition Liquid phase Composition (molar ratio) (% bymass) (% by mass) No. ratio MgO SiO₂ MgO SiO₂ B₂O₃ Li₂O Comparative 95 22 38.1 56.9 4.5 0.5 Example 11 Comparative 94 2 2 37.7 56.3 4.5 1.5Example 12

TABLE 4 Sintering Holding Bulk Temperature Time Density FrequencyDielectric No. (° C.) (hr) (g/cm³) (GHz) constant Q Qf Comparative 953 1Un-sintered — — — — Example 11 Comparative 953 1 3.03 18.8 6.86 410 7716Example 12

INDUSTRIAL APPLICABILITY

As detailed above, the low temperature sintering ceramic compositionaccording to the invention, as a result of the use of oxides of Bi andLi as a liquid phase formation component, realized the low temperaturesintering properties in the ceramic composition that was mainlyconstituted of the forsterite system crystal phase and/or enstatitesystem crystal phase. Furthermore, it was found that even when Bi₂O₃ wasintroduced much, the dielectric loss was not deteriorated, and thereby ahigh Qf value could be realized. Accordingly, the ceramic compositionaccording to the invention, being most suitable as a low loss LTCC (lowtemperature co-firing ceramics) material that has the dielectricconstant (9 or less) and high Qf (10,000 or more) that can be utilizedin a high frequency region of 17 GHz or more, can be used in variouskinds of microwave circuit elements and so on. Furthermore, the ceramiccomposition can be sintered at a temperature in the range of from 850 to1000° C.; accordingly, wiring made of Cu, Au, Ag and so on can be formedaccording to co-firing.

1. A low temperature sintering ceramic composition containing Mg, Si, Biand Li as constituent elements, wherein the composition comprises MgOand SiO₂ in sum total in the range of from 64.0 to 99.2% by mass; Bi₂O₃in the range of from 0.4 to 33.0% by mass; Li₂O in the range of from 0.4to 3.0% by mass; and MgO and SiO₂ are contained in the molar ratio offrom 2:1 to 2:3.5, at least part thereof being contained as a complexoxide of Mg and Si.
 2. The low temperature sintering ceramic compositionaccording to claim 1, wherein the composition comprises MgO and SiO₂ insum total in the range of from 75.0 to 98.0% by mass; Bi₂O₃ in the rangeof from 1.5 to 24.5% by mass; and Li₂O in the range of from 0.5 to 3.0%by mass.
 3. The low temperature sintering ceramic composition accordingto claim 1, wherein the complex oxide is a forsterite system crystalphase and at least part of Bi₂O₃ and Li₂O is contained as a Bi₂O₃—SiO₂system crystal phase and a Li₂O—SiO₂ system crystal phase.
 4. The lowtemperature sintering ceramic composition according to claim 3, whereinthe forsterite system crystal phase is contained by 60% or more of atotal volume of the ceramic.
 5. The low temperature sintering ceramiccomposition according to claim 1, wherein a Qf value is 10,000 or more.6. An electronic component comprising a wiring pattern on the lowtemperature sintering ceramic composition according to claim
 1. 7. Theelectronic component according to claim 6, wherein the wiring is formedby sintering a conductive paste containing at least one metal selectedfrom Ag, Au and Cu.
 8. A method of fabricating a low temperaturesintering ceramic composition comprising: molding a raw material powdercontaining one or both of a mixture of MgO and SiO₂ that contains MgOand SiO₂ at a molar ratio in the range of from 2:1 to 2:3.5 and acomplex oxide thereof in the range of from 64.0 to 99.2% by mass, Bi₂O₃in the range of from 0.4 to 33.0% by bass and Li₂O in the range of from0.4 to 3.0% by mass into a predetermined shape followed by sintering ata temperature in the range of from 850 to 1000° C.
 9. The methodaccording to claim 8, wherein the raw material powders are fine powdershaving a particle size of 2.0 μm or less.
 10. The low temperaturesintering ceramic composition according to claim 1, wherein the complexoxide is a enstatite system crystal phase; and at least part of Bi₂O₃and Li₂O is contained as a Bi₂O₃—SiO₂ system crystal phase and aLi₂O—SiO₂ system crystal phase.
 11. The low temperature sinteringceramic composition according to claim 3, wherein the enststite systemcrystal phase is contained by 60% or more of a total volume of theceramic.